Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The plasma-ACTH of healthy test persons and of patients suffering from spontaneous hypertension were measured by RIA. In the latter group it was decreased in 17 of 21 cases, where as the serum cortisol was increased. Further examinations are necessary for the clarification of this phenomenon. Clonidine clearly reduced plasma ACTH, serum cortisol and renin activity.
 ...
PMID:[Corticotropin studies in essential hypertension]. 631 85

The sympathetic nervous system (SNS) plays a major role in blood pressure regulation. Although the exact relationship of the SNS to the etiology of hypertension remains undetermined, many of the agents used to treat hypertension interfere with this system. Clonidine, methyldopa, guanethidine, and reserpine decrease SNS tone whereas hydralazine, minoxidil, and hydrochlorothiazide increase it. Most evidence suggests that beta-adrenergic blocking agents decrease SNS activity. The effect of prazosin and captopril on the SNS requires further study. The appropriate use of these antihypertensive agents requires a knowledge of their sites of action and the physiological reflexes they induce. Efficacy, toxicity, and effective drug combinations can be predicted based on their mechanism of action and effect on SNS activity.
 ...
PMID:Effect of antihypertensive therapy on sympathetic nervous system activity in patients with essential hypertension. 631 67

These studies were undertaken to clarify the role of the central and peripheral sympathetic nervous system and the renin-aldosterone system on the onset and maintenance of high blood pressure in essential hypertension (EH), and the following examinations were performed: 1) Urinary free norepinephrine and epinephrine excretion (UNEf and UEf), urinary conjugated norepinephrine and epinephrine excretion (UNEconj and UEconj), plasma norepinephrine and epinephrine concentration (PNE and PE), plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were measured in 52 patients with EH, who were divided into two groups (borderline EH: b-EH, and sustained EH: s-EH), and fifteen normals (N). 2) Cardiac index (CI), total peripheral resistance index (TPRI), appearance time, mean transit time and stroke index (SI) were determined by the dye-dilution method in eight patients with b-EH, ten patients with s-EH and ten N. 3) Clonidine was administered orally in a single dose of 150 micrograms to seven patients with s-EH and three patients with b-EH, and PNE, PE and growth hormone (GH) were measured before and after the administration. 4) Isoproterenol was infused intravenously in a dose of 0.02 microgram/kg/min for 30 min to 18 patients with s-EH and six N, then plasma cyclic AMP (c-AMP) and PRA were determined before, during and after the infusion. 5) Methacholine was injected intramuscularly in a dose of 10 mg to seven N, and PNE, PE and PRA were measured before and after the injection. There were no significant differences of PNE, PE, UNEf and UEf among the three groups (b-EH, s-EH and N), but UNEconj in both b-EH and s-EH was higher than in N (b-EH: p less than 0.1, s-EH: p less than 0.05). PRA in s-EH was slightly lower not only in N but also in b-EH. PAC in b-EH and s-EH was slightly lower than in N. The difference of PAC between b-EH and s-EH was not found. CI and SI were higher than in N (p less than 0.05), but TPRI was normal. In s-EH, TPRI was slightly elevated as compared with b-EH (p less than 0.1). In s-EH, clonidine caused a significant lowering of both blood pressure and PNE with a simultaneously marked increment of GH; on the other hand, in b-EH blood pressure and PNE did not change significantly in spite of the distinct rise of GH. After the isoproterenol infusion, PRA and c-AMP increased, and there was a significant correlation between the initial level of PRA and the maximal increment of PRA after the infusion in both s-EH and N.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:[Studies on the role of the central and peripheral sympathetic nervous system and the renin-aldosterone system on the onset and maintenance of high blood pressure in essential hypertension]. 632 58

The systemic, cardiovascular hemodynamic and biochemical interactions between clonidine and minoxidil were studied in ten patients with refractory and/or accelerated hypertension. Clonidine in oral doses of 150 to 900 micrograms/day decreased mean blood pressure (MAP) 18.6 mm Hg (p less than 0.01), average heart rate (HR) 16.4 bpm (p less than 0.01), limb blood flow 1.63 ml/100 g min (p less than 0.05), plasma renin activity (PRA) 1.13 ng/ml/hr (p less than 0.025), and urinary noradrenaline excretion rate 16.45 micrograms/24hr (p less than 0.05). Clonidine increased the preejection period index (PEPI) 12.4 msec ( p less than 0.001), but did not alter cardiac index (CI), total peripheral resistance index (TPRI), limb vascular resistance nor dopamine beta-hydroxylase activity. When minoxidil in oral doses of 5 to 22.5 mg was added, a further decrease in MAP of 24.2 mm Hg (p less than 0.01) was observed; PEPI decreased 20.6 msec (p less than 0.01), limb blood flow decreased 13.2 mm Hg/min 100 g/ml (p less than 0.05), and total peripheral resistance index decreased 13.3 mm Hg/min m2/L (p less than 0.05). Minoxidil increased average heart rate 8.2 bpm (p less than 0.05), PRA 1.68 ng/ml/hr (p less than 0.05) and urinary noradrenaline excretion rate 5.0 micrograms/24 hr (p less than 0.01). Limb blood flow, cardiac index and dopamine beta hydroxylase activity were not significantly altered by minoxidil. Neither clonidine nor minoxidil affected cardiovascular responses to treadmill exercise. We concluded that clonidine is a useful alternative agent to block a minoxidil-induced increase in sympathetic nervous activity.
 ...
PMID:Cardiovascular hemodynamic interactions between clonidine and minoxidil in hypertensive patients. 633 28

Clonidine was given to patients with essential hypertension, renovascular hypertension, and hypertension with parenchymal renal disease. The drug was effective in all groups but was more effective in patients with high plasma renin concentration. Renal function did not deteriorate when the drug was used, and there was an increase in renal blood flow and a small increase in glomerular filtration rate in those with renovascular or essential hypertension. These changes may have been due to falls in plasma renin. Clonidine can be used in patients with renal disease and does not cause worsening of renal function.
 ...
PMID:The use of centrally acting antihypertensive drugs in patients with renal disease. 633 30

Antihypertensive medications have a variable effect on renal hemodynamics and may contribute to renal insufficiency in some patients. Since clonidine has actually been found to improve renal hemodynamics in patients with essential hypertension, we studied the effects of clonidine therapy in patients with renal transplant hypertension. Baseline measurements of BP and renal hemodynamics were made in six patients after two weeks of therapy with furosemide. Clonidine was then added and titrated until BP was controlled. Repeated measurements of renal hemodynamics were made four and 16 weeks after clonidine therapy was begun. Glomerular filtration and effective renal plasma flow as assessed by inulin and aminohippurate sodium clearances were preserved during prolonged clonidine therapy.
 ...
PMID:Effect of clonidine therapy on renal hemodynamics in renal transplant hypertension. 637 12

The effects of 300 micrograms oral clonidine were studied in 15 hypertensive patients with unilateral renal involvement -nine had renal artery stenosis and six renal parenchymal disease. After clonidine blood pressure fell substantially in both groups, with the maximum fall in the fourth hour and effects persisting after 6 h. Levels of plasma renin activity were considerably higher in the renal artery stenosis patients and remained unchanged during the study; there was a progressive fall in levels in each of the patients with renal parenchymal disease. Plasma noradrenaline levels fell in both groups. Clonidine therefore lowers blood pressure in patients with unilateral renal artery stenosis and renal parenchymal disease. The known pharmacological effects of clonidine would thus favour either an increase or an inappropriate maintenance of central pressor activity as a contributory factor to the hypertension in both groups. The central mechanisms raising blood pressure may result not only from high angiotensin II levels but to other less well defined effects, from an ischaemic or diseased kidney. The lack of fall of plasma renin activity in the renal artery stenosis patients probably indicates the greater influence of ischaemia and renal baroreceptor stimulation over sympathetically mediated renin release.
 ...
PMID:Clonidine in unilateral renal artery stenosis and unilateral renal parenchymal disease--similar antihypertensive but different renin suppressive effects. 640 Jan 11

The effects and safety of using oral nifedipine 10-20 mg as acute antihypertensive treatment were studied in a single-blind placebo-controlled study of 25 consecutive patients with very high blood pressure requiring emergency reduction. In addition the effect of this treatment on cerebral blood flow was investigated using xenon-133 in 10 patients randomly allocated to receive oral nifedipine or intravenous clonidine. Whereas placebo did not alter the blood pressure, oral nifedipine significantly reduced the systolic and diastolic blood pressures in all 25 patients (from 221 +/- 22/126 +/- 14 mm Hg to 152 +/- 20/89 +/- 12 mm Hg after 30 minutes, p less than 0.001). Heart rate increased from 74 +/- 11 to 84 +/- 11 beats/minute (p less than 0.01); this effect was inversely related to age (r = -0.65, p less than 0.01). The falls in systolic and diastolic blood pressures were closely related to the blood pressures before treatment ) r = 0.67, p less than 0.001 for systolic, and r = -0.58, p less than 0.01 for diastolic values). No serious unwanted effects were observed. Measurement of cerebral blood flow after nifedipine showed an increase in flow in four out of five patients. Clonidine, by contrast, reduced cerebral blood flow in all patients by up to 28%. Nifedipine is a simple, effective, and safe alternative drug for managing hypertensive emergencies, especially when continuous monitoring of the patient cannot be guaranteed.
 ...
PMID:Nifedipine in hypertensive emergencies. 640 42

This article describes in vitro and in vivo performance of two transdermal drug delivery systems. Transderm -Nitro delivers nitroglycerin for the treatment and prevention of angina for 24 hours following a single application. In a three-way crossover study comparing Transderm -Nitro with two other transdermal nitroglycerin products, mean plasma levels of drug were similar 0.5 and 6 hours after application; however, with Transderm -Nitro the area under the plasma concentration curve was highest and the coefficient of variation was least. A transdermal therapeutic system for delivering clonidine ( Catapres -TTS) is used for the treatment of hypertension. In a two-way crossover study comparing Catapres -TTS and oral Catapres , plasma levels of clonidine with use of the transdermal system reached a steady-state value in 2 to 3 days and remained steady for the duration of the wearing period; plasma levels with oral Catapres , however, fluctuated markedly. The ratio of maximum to minimum plasma levels during a dosing interval was 2 for oral Catapres and approximately 1 for Catapres -TTS. The potential use of intact skin as a route of entry for controlled delivery of drugs to the systemic circulation is promising.
 ...
PMID:Pharmacokinetics of nitroglycerin and clonidine delivered by the transdermal route. 642 8

Clonidine administration by i.v. infusion in 12 patients with hypertension emergencies (diastolic blood pressure over 130 mmHg) resulted in the normalization of blood pressure (BP) in all patients. Lowering of BP was associated with a reduction in total and lower limb vascular resistance. Heart rate showed a slight and brief decrease. Cardiac performance (determined by radionuclide angiocardiography) was improved as indicated by the significant increase of ejection fraction and decrease of both end-diastolic and end-systolic volumes. The dosage of clonidine was progressively increased until a normal BP (mean BP less than or equal to 105 mmHg) was obtained. In all patients a normal BP was achieved and in none was an initial hypertension effect observed. The total mean dose required for control of BP was 382.5 +/- 98.3 micrograms, administered over a mean period of 26.5 +/- 4.6 min. Side-effects, represented by dry mouth and drowsiness, were well tolerated and of short duration. It is concluded that clonidine is an effective and safe alternative in the treatment of hypertensive emergencies.
 ...
PMID:Changes in cardiac function after effective treatment of hypertensive emergencies with i.v. clonidine. 653 50


<< Previous 1 2 3 4 5 6 7 8 9 10